Methods for depositing a transition metal chalcogenide film on a substrate by a cyclical deposition process

ABSTRACT

Systems for depositing a transition metal chalcogenide film on a substrate by cyclical deposition process are disclosed. The methods may include, contacting the substrate with at least one transition metal containing vapor phase reactant comprising at least one of a hafnium precursor, or a zirconium precursor, and contacting the substrate with at least one chalcogen containing vapor phase reactant. Semiconductor device structures including a transition metal chalcogenide film deposited by the methods of the disclosure are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to, U.S. patent application Ser. No. 16/193,789 filed Nov. 16, 2018 titled METHODS FOR DEPOSITING A TRANSITION METAL CHALCOGENIDE FILM ON A SUBSTRATE BY A CYCLICAL DEPOSITION PROCESS, the disclosure of which is hereby incorporated by reference in its entirety.

PARTIES OF JOINT RESEARCH AGREEMENT

The invention claimed herein was made by, or on behalf of, and/or in connection with a joint research agreement between the University of Helsinki and ASM Microchemistry Oy. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.

FIELD OF INVENTION

The present disclosure relates generally to methods for depositing a transition metal chalcogenide film on a substrate by a cyclical deposition process and in particular to the cyclical deposition of transition metal chalcogenides comprising hafnium or zirconium. The disclosure also relates to semiconductor device structures including a transition metal chalcogenide film deposited by a cyclical deposition process.

BACKGROUND OF THE DISCLOSURE

The interest in two-dimensional (2D) materials has increased dramatically in recent years due to their potential in improving performance in next generation electronic devices. For example, graphene has been the most studied 2D material to date and exhibits high mobility, transmittance, mechanical strength, and flexibility. However, the lack of a band gap in pure graphene has limited its performance in semiconductor device structures, such as transistors. Such limitations in graphene have stimulated research in alternative 2D materials as analogues of graphene. Recently, transition metal chalcogenides, and particularly transition metal dichalcogenides, have attracted considerable research attention as an alternative to graphene. Transition metal dichalcogenides may have stoichiometry of MX₂, which describes a transition metal (M) sandwiched between two layers of chalcogen atoms (X), with strong in-plane covalent bonding between the metal-chalcogen and weak out-of-plane van der Waals bonding between the layers.

However, there are few scalable, low temperature methods to produce 2D materials. Currently, mechanical exfoliation of bulk crystals is the most commonly used method of formation, but although this method produces good quality crystals, the method is unable to produce continuous films and is very labor intensive, making such a method not viable for industrial production. Chemical vapor deposition (CVD) has been used to deposit 2D materials, but current CVD processes for some metal chalcogenides, such as, for example, hafnium disulfide (HfS₂), operate at temperatures between 900° C. and 1000° C. and are unable to produce continuous, large area 2D materials.

Accordingly, methods are desirable that are capable of producing 2D materials, at a reduced deposition temperature, and with atomic level film thickness control.

SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

In some embodiments, methods for depositing a transition metal chalcogenide film on a substrate by a cyclical deposition process are provided. The methods may comprise: contacting the substrate with at least one transition metal containing vapor phase reactant comprising at least one of a hafnium precursor, or a zirconium precursor; and contacting the substrate with at least one chalcogen containing vapor phase reactant, wherein the temperature of the substrate during the contacting steps is below about 450° C.

The embodiments of the disclosure also provide semiconductor device structures comprising a transition metal chalcogenide film deposited by the methods described herein.

For the purpose of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a process flow diagram illustrating an exemplary cyclical deposition method according to the embodiments of the disclosure;

FIG. 2 illustrates the growth rate, crystallinity, and composition of exemplary hafnium chalcogenide films deposited at various deposition temperatures according to the embodiments of the disclosure;

FIG. 3 illustrates the growth rate, crystallinity, and composition of exemplary zirconium chalcogenide films deposited at various deposition temperatures according to the embodiments of the disclosure;

FIG. 4 illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary hafnium chalcogenide films deposited at various deposition temperatures according to the embodiments of the disclosure;

FIG. 5 illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary zirconium chalcogenide films deposited at various deposition temperatures according to the embodiments of the disclosure;

FIG. 6 illustrates the ambient stability over time of both a bare zirconium chalcogenide film and a zirconium chalcogenide film capped with a metal silicate capping layer according to the embodiments of the disclosure;

FIG. 7A illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary zirconium chalcogenide films deposited utilizing a different number of deposition cycles without a capping layer deposited over the chalcogenide film according to the embodiments of the disclosure;

FIG. 7B illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary zirconium chalcogenide films deposited utilizing a different number of deposition cycles with a capping layer deposited over the chalcogenide film according to the embodiments of the disclosure;

FIG. 8 illustrates an exemplary semiconductor device structure including a transition metal chalcogenide film deposited according to the embodiments of the disclosure; and

FIG. 9 illustrates an exemplary reaction system which may be utilized to deposit a transition metal chalcogenide film according to the embodiments of the disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “substrate” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit or a film may be formed.

As used herein, the term “cyclic deposition” may refer to the sequential introduction of precursors (reactants) into a reaction chamber to deposit a film over a substrate and includes deposition techniques such as atomic layer deposition and cyclical chemical vapor deposition.

As used herein, the term “atomic layer deposition” (ALD) may refer to a vapor deposition process in which deposition cycles, preferably a plurality of consecutive deposition cycles, are conducted in a process chamber. Typically, during each cycle the precursor is chemisorbed to a deposition surface (e.g., a substrate surface or a previously deposited underlying surface such as material from a previous ALD cycle), forming a monolayer or sub-monolayer that does not readily react with additional precursor (i.e., a self-limiting reaction). Thereafter, if necessary, a reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the process chamber for use in converting the chemisorbed precursor to the desired material on the deposition surface. Typically, this reactant is capable of further reaction with the precursor. Further, purging steps may also be utilized during each cycle to remove excess precursor from the process chamber and/or remove excess reactant and/or reaction byproducts from the process chamber after conversion of the chemisorbed precursor. Further, the term “atomic layer deposition,” as used herein, is also meant to include processes designated by related terms, such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy when performed with alternating pulses of precursor composition(s), reactive gas, and purge (e.g., inert carrier) gas.

As used herein, the term “cyclical chemical vapor deposition” may refer to any process wherein a substrate is sequentially exposed to two or more volatile precursors, which react and/or decompose on a substrate to produce a desired deposition.

As used herein, the term “chalcogen containing vapor phase reactant” may refer to a reactant (precursor) containing a chalcogen, wherein a chalcogen is an element from Group VI of the periodic table including sulfur, selenium, and tellurium.

As used herein, the term “film” and “thin film” may refer to any continuous or non-continuous structures and material deposited by the methods disclosed herein. For example, “film” and “thin film” could include 2D materials, nanolaminates, nanorods, nanotubes, or nanoparticles or even partial or full molecular layers or partial or full atomic layers or clusters of atoms and/or molecules. “Film” and “thin film” may comprise material or a layer with pinholes, but still be at least partially continuous.

As used herein, the term “2D material” or “two-dimensional material” may refer to a nanometer scale crystalline material one, two or three atoms in thickness. In addition, “2D materials” or “two-dimensional material” may also refer to an ordered nanometer scale crystalline structure composed of multiple monolayers of crystalline materials of approximately three atoms in thickness per monolayer.

As used herein, the term “halide precursor” may refer to a transition metal halide precursor comprising a halide component including at least one of chlorine, iodine, or bromine.

As used herein, the term “metalorganic precursor” may refer to a transition metal metalorganic precursor wherein “metalorganic” or “organometallic” are used interchangeably and may refer to organic compounds containing a metal species. Organometallic compounds may be considered to be subclass of metalorganic compounds having direct metal-carbon bonds.

A number of example materials are given throughout the embodiments of the current disclosure; it should be noted that the chemical formulas given for each of the example materials should not be construed as limiting and that the non-limiting example materials given should not be limited by a given example stoichiometry.

The embodiments of the disclosure may include methods for depositing a transition metal chalcogenide on a substrate by a cyclical deposition process and particularly methods for depositing transition metal chalcogenide films comprising either a hafnium component or a zirconium component by atomic layer deposition processes. As non-limiting examples, hafnium disulfide (HfS₂) and zirconium disulfide (ZrS₂) are emerging materials, which have a 2D crystal structure, similar to the well-known transition metal dichalcogenides (TMDCs), such as, for example, molybdenum disulfide (MoS₂). In comparison to the most studied 2D material, graphene, hafnium disulfide and zirconium disulfide may have a sizable band gap, which makes such exemplary transition metal chalcogenide films more suitable in semiconductor device structures, such as, for example, field effect transistors (FETs).

Current methods for forming transition metal chalcogenide films are not suitable for forming high quality, conformal, low temperature thin films. Transition metal chalcogenide crystals may be formed by mechanical exfoliation of a bulk transition metal chalcogenide crystal, but such methods are not suitable for forming transition metal chalcogenide films to a thickness accuracy on the atomic scale on suitable substrates. In addition, chemical vapor deposition of some transition metal chalcogenide films has been demonstrated but such processes operate at high deposition temperatures (e.g., greater than 900° C. for HfS₂) and are unsuitable to produce nanoscale, conformal, thin films.

Cyclical deposition methods, such as cyclical chemical vapor deposition and atomic layer deposition techniques, are inherently scalable and offer atomically accurate film thickness control, which is crucial in the deposition of high quality 2D materials. In addition, cyclic deposition methods with surface control in reactions, such as atomic layer deposition, are characteristically conformal, thereby providing the ability to uniformly coat three dimensional structures.

In addition, transition metal chalcogenide films may be susceptible to oxidation either during the deposition process or when exposed to ambient conditions. Therefore cyclical deposition methods may be desirable, which do not incorporate transition metal oxide phases into the chalcogenide film during deposition. In addition, methods are highly desirable to prevent the oxidation of the transition metal chalcogenide films when exposed to ambient conditions.

Accordingly, methods are desired which are capable of depositing transition metal chalcogenide films at reduced temperatures, conformally, and with atomic thickness accuracy. In addition, semiconductor device structures comprising a transition metal chalcogenide film are desirable.

A non-limiting example embodiment of a cyclical deposition process may include ALD, wherein ALD is based on typically self-limiting reactions, whereby sequential and alternating pulses of reactants are used to deposit about one atomic (or molecular) monolayer of material per deposition cycle. The deposition conditions and precursors are typically selected to provide self-saturating reactions, such that an adsorbed layer of one reactant leaves a surface termination that is non-reactive with the vapor phase reactants of the same reactant. The substrate is subsequently contacted with a different reactant that reacts with the previous termination to enable continued deposition. Thus, each cycle of alternating pulsed reactants typically leaves no more than about one monolayer of the desired material. However, as mentioned above, the skilled artisan will recognize that in one or more ALD cycles more than one monolayer of material may be deposited, for example, if some gas phase reactions occur despite the alternating nature of the process.

In an ALD-type process for depositing a transition metal chalcogenide film, one deposition cycle may comprise exposing the substrate to a first vapor phase reactant, removing any unreacted first reactant and reaction byproducts from the reaction space, and exposing the substrate to a second vapor phase reactant, followed by a second removal step. The first reactant may comprise a transition metal containing precursor, such as a hafnium precursor or a zirconium precursor, and the second reactant may comprise a chalcogen containing precursor.

Precursors may be separated by inert gases, such as argon (Ar), or nitrogen (N₂), to prevent gas phase reactions between reactants and enable self-saturating surface reactions. In some embodiments, however, the substrate may be moved to separately contact a first vapor phase reactant and a second vapor phase reactant. Because the reactions self-saturate, strict temperature control of the substrates and precise dosage control of the precursor may not be required. However, the substrate temperature is preferably such that an incident gas species does not condense into monolayers nor decompose on the substrate surface. Surplus chemicals and reaction byproducts, if any, are removed from the substrate surface, such as by purging the reaction space or by moving the substrate, before the substrate is contacted with the next reactive chemical. Undesired gaseous molecules can be effectively expelled from the reaction space with the help of an inert purging gas. A vacuum pump may be used to assist in the purging process.

Reactors capable of being used to deposit or grow thin films can be used for the deposition. Such reactors include ALD reactors, as well as CVD reactors equipped with appropriate equipment and means for providing the precursors. According to some embodiments, a showerhead reactor may be used. In some embodiments the reactor is a spatial ALD reactor, in which the substrates moves or rotates during processing.

In some embodiments a batch reactor may be used. In some embodiments, a vertical batch reactor is utilized in which the boat rotates during processing. Thus, in some embodiments, the wafers rotate during processing. In other embodiments, the batch reactor comprises a mini-batch reactor configured to accommodate 10 or fewer wafers, 8 or fewer wafers, 6 or fewer wafers, 4 or fewer wafers, or 2 wafers. In some embodiments in which a batch reactor is used, wafer-to-wafer non-uniformity is less than 3% (1 sigma), less than 2%, less than 1% or even less than 0.5%.

The deposition processes described herein can optionally be carried out in a reactor or reaction chamber connected to a cluster tool. In a cluster tool, because each reaction chamber is dedicated to one type of process, the temperature of the reaction chamber in each module can be kept constant, which improves the throughput compared to a reactor in which the substrate is heated up to the process temperature before each run. Additionally, in a cluster tool it is possible to reduce the time to pump the reaction space to the desired process pressure levels between substrates.

A stand-alone reactor can be equipped with a load-lock. In that case, it is not necessary to cool down the reaction chamber between each run. In some embodiments, a deposition process for depositing a film comprising a transition metal chalcogenide film may comprise a plurality of deposition cycles, for example ALD cycles.

In some embodiments, cyclical deposition processes are used to deposit transition metal chalcogenide thin films on a substrate and the cyclical deposition process may be an ALD type process. In some embodiments, the cyclical deposition may be a hybrid ALD/CVD or cyclical CVD process. For example, in some embodiments the deposition rate of the ALD process may be low compared with a CVD process. One approach to increase the deposition rate may be that of operating at a higher substrate temperature than that typically employed in an ALD process, resulting in a chemical vapor deposition process, but still taking advantage of the sequential introduction of precursors, such a process may be referred to as cyclical CVD. In some embodiments, a cyclical CVD process may comprise the introduction of two or more precursors into the reaction chamber wherein there may be a time period of overlap between the two or more precursors in the reaction chamber resulting in both an ALD component of the deposition and a CVD component of the deposition. For example, a cyclical CVD process may comprise the continuous flow of a first precursor and the periodic pulsing of a second precursor into the reaction chamber.

According to some embodiments of the disclosure, ALD processes are used to deposit transition metal chalcogenide films on a substrate, such as an integrated circuit workpiece. In some embodiments, each ALD cycle may comprise two distinct deposition steps or phases. In a first phase of the deposition cycle (“the metal phase”), the substrate surface on which deposition is desired is contacted with a first vapor phase reactant comprising at least one of a hafnium precursor, or zirconium precursor, which chemisorbs onto the substrate surface, forming no more than about one monolayer of reactant species on the surface of the substrate. In a second phase of the deposition cycle (“the chalcogen phase”), the substrate surface on which deposition is desired is contacted with a second vapor phase reactant comprising at least one chalcogen containing vapor phase reactant which reacts with the previously chemisorbed species to form a transition metal chalcogenide film.

In some embodiments of the disclosure, the transition metal containing vapor phase reactant comprises at least one of a hafnium precursor, or a zirconium precursor. In some embodiments, the hafnium precursor, or the zirconium precursor, comprises at least one of a halide precursor, or a metalorganic precursor. In some embodiments, the metalorganic precursor may comprise at least one of an alkylamide precursor, or a cyclopentadienyl-ligand containing precursor. In some embodiments, the hafnium precursor, or zirconium precursor, may comprise a heteroleptic precursor.

In some embodiments, the hafnium precursor may comprise at least one of a hafnium halide precursor, a hafnium metalorganic precursor, or an organometallic hafnium precursor.

In some embodiments, the hafnium halide precursor may comprise at least one halide ligand while the rest of the ligands are different, such as metalorganic or organometallic ligands as described later herein. In some embodiments, the hafnium halide precursor may comprise one, two, three or four halide ligands such as chloride ligands.

In some embodiments, the hafnium halide precursor may comprise at least one of a hafnium chloride, a hafnium iodide, or a hafnium bromide. In some embodiments, the hafnium chloride may comprise hafnium tetrachloride (HfCl₄). In some embodiments, the hafnium iodide may comprise hafnium tetraiodide (HfI₄). In some embodiments, the hafnium bromide may comprise hafnium tetrabromide (HfBr₄).

In some embodiments, the hafnium metalorganic precursor may comprise at least one of a hafnium alkylamide precursor, a hafnium cyclopentadienyl-ligand containing precursor, or other metalorganic hafnium precursors.

In some embodiments, the hafnium alkylamide precursor may be selected from the group comprising tetrakis(ethylmethylamido)hafnium (Hf(NEtMe)₄), tetrakis(dimethylamido)hafnium (Hf(NMe₂)₄), or tetrakis(diethylamido)hafnium (Hf(NEt₂)₄).

In some embodiments of the disclosure, the hafnium cyclopentadienyl-ligand containing precursor may be selected from the group comprising (tris(alkylamido)cyclopentadienylhafnium, such as (tris(dimethylamido)cyclopentadienylhafnium HfCp(NMe₂)₃, or bis(methylcyclopentadienyl)methoxymethyl hafnium (MeCp)₂Hf(CH)₃(OCH₃) or derivatives of those, such as ones in which there is one or more hydrocarbons, such as alkyls, attached to the cyclopentadienyl-ligand of those precursors, or other alkyl groups in alkylamido-ligand.

In some embodiments, the hafnium precursor may have the formula;

HfL₁L₂L₃L₄

wherein each of the L ligands through L1-L4 can be independently selected to be

-   -   a) Halide, such as chloride, bromide or iodide     -   b) Alkylamido, such as dimethylamido (—NMe₂), diethylamido         (—NEt₂), ethylmethylamido (—NEtMe)     -   c) Amidinate, such as N,N′-dimethylformamidinate     -   d) Guanidinate, such as         N,N′-diisopropyl-2-ethylmethylamidoguanidinate     -   e) Cyclopentadienyl or derivatives of those, such as         cyclopentadienyl or methylcyclopentadienyl or other         alkylsubstituted cyclopentadienyl ligands     -   f) Cycloheptadienyl or -trienyl-based, such as a         cycloheptatrienyl or cycloheptadienyl     -   g) Alkyl, such as C1-C5 alkyl, for example methyl, mostly in         case of heteroleptic precursors     -   h) Alkoxide, such as methoxide (—OMe), ethoxide (—OEt),         isopropoxide (—O^(i)Pr), n-butoxide (—OBu) or tert-butoxide         (—O^(t)Bu)     -   i) Betadiketonate, such as         (2,2,6,6-tetramethyl-3,5-heptanedionato) (thd)     -   j) Donor-functionalized alkoxide, such as dimethylethanolamine

In some embodiments of the disclosure, the hafnium precursor comprises one or more bidentate ligands which are bonded to Hf through nitrogen and/or oxygen atoms. In some embodiments, the hafnium precursor comprises one or more ligands which are bonded to Hf through nitrogen, oxygen, and/or carbon.

In some embodiments, the zirconium precursor may comprise at least one of a zirconium halide precursor, a zirconium metalorganic precursor, or an organometallic zirconium precursor.

In some embodiments, the zirconium halide precursor may comprise at least one of a zirconium chloride, a zirconium iodide, or a zirconium bromide. In some embodiments, the zirconium chloride may comprise zirconium tetrachloride (ZrCl₄). In some embodiments, the zirconium halide precursor may comprise at least one halide ligand while the rest of the ligands are different, such as metalorganic or organometallic ligands as described later herein. In some embodiments, the zirconium halide precursor may comprise one, two, three or four halide ligands such as chloride ligands. In some embodiments, the zirconium iodide may comprise zirconium tetraiodide (ZrI₄). In some embodiments, the zirconium bromide may comprise zirconium tetrabromide (ZrBr₄).

In some embodiments, the zirconium metalorganic precursor may comprise at least one of a zirconium alkylamide precursor, a zirconium cyclopentadienyl-ligand containing precursor, or other metalorganic zirconium precursors.

In some embodiments, the zirconium alkylamide precursor may be selected from the group comprising tetrakis(ethylmethylamido)zirconium (Zr(NEtMe)₄), tetrakis(dimethylamido)zirconium (Zr(NMe₂)₄), or tetrakis(diethylamido)zirconium (Zr(NEt₂)₄).

In some embodiments of the disclosure, the zirconium cyclopentadienyl-ligand containing precursor may be selected from the group comprising (tris(alkylamido)cyclopentadienylzirconium, such as (tris(dimethylamido)cyclopentadienyl zirconium ZrCp(NMe₂)₃, or bis(methylcyclopentadienyl)methoxymethyl zirconium (MeCp)₂Zr(CH)₃(OCH₃), or derivatives of those, such as ones in which there is one or more hydrocarbons, such as alkyls, attached to the cyclopentadienyl-ligand of those precursors, or other alkyl groups in alkylamido-ligand.

In some embodiments, the zirconium precursor may have the formula;

ZrL₁L₂L₃L₄

-   -   wherein each of the L ligands through L1-L4 can be independently         selected to be     -   k) Halide, such as chloride, bromide or iodide     -   l) Alkylamido, such as dimethylamido (—NMe₂), diethylamido         (—NEt₂), ethylmethylamido (—NEtMe)     -   m) Amidinate, such as N,N′-dimethylformamidinate     -   n) Guanidinate, such as         N,N′-diisopropyl-2-ethylmethylamidoguanidinate     -   o) Cyclopentadienyl or derivatives of those, such as         cyclopentadienyl or methylcyclopentadienyl or other         alkylsubstituted cyclopentadienyl ligands     -   p) Cycloheptadienyl or -trienyl-based, such as a         cycloheptatrienyl or cycloheptadienyl     -   q) Alkyl, such as C1-C5 alkyl, for example methyl, mostly in         case of heteroleptic precursors     -   r) Alkoxide, such as methoxide (—OMe), ethoxide (—OEt),         isopropoxide (—O^(i)Pr), n-butoxide (—OBu) or tert-butoxide         (—O^(t)Bu)     -   s) Betadiketonate, such as         (2,2,6,6-tetramethyl-3,5-heptanedionato) (thd)     -   t) Donor-functionalized alkoxide, such as dimethylethanolamine

In some embodiments of the disclosure, the zirconium precursor comprises one or more bidentate ligands which are bonded to Zr through nitrogen and/or oxygen atoms. In some embodiments, the zirconium precursor comprises one or more ligands which are bonded to Zr through nitrogen, oxygen, and/or carbon.

In some embodiments, exposing the substrate to the transition metal containing vapor phase reactant may comprise, pulsing the transition metal precursor over the substrate for a time period between about 0.01 second and about 60 seconds, between about 0.05 seconds and about 10 seconds, or between about 0.1 seconds and about 5.0 seconds. In addition, during the pulsing of the transition metal precursor over the substrate the flow rate of the transition metal precursor may be less than 2000 sccm, or less than 500 sccm, or even less than 100 sccm. In addition, during the pulsing of the transition metal precursor over the substrate the flow rate of the transition metal precursor may be from about 1 to about 2000 sccm, from about 5 to about 1000 sccm, or from about 10 to about 500 sccm.

In some embodiments, the purity of the transition metal containing vapor phase reactants may influence the composition of the deposited film and therefore high purity sources of the transition metal containing vapor phase reactants may be utilized. For example, in some embodiments, the transition metal vapor phase reactant may comprise a hafnium precursor or a zirconium precursor with a purity of greater than or equal to 99.99%.

In some embodiments, the transition metal containing vapor phase reactant may be contained in a vessel and one or more heaters may be associated with the vessel to control the temperature of the metal precursor and subsequently the partial pressure of the metal precursor. In some embodiments of the disclosure, the metal precursor within the vessel may be heated to a temperature between approximately 20° C. and approximately 300° C. For example, in some embodiments, the metal precursor may be heated to a temperature from about 30° C. to about 250° C., or from about 40° C. to about 225° C., or from about 50° C. to about 150° C., depending on the precursor choice.

In some embodiments, a vessel containing the metal precursor may be connected to a source of one or more carrier gases. The carrier gas may be introduced into the vessel and drawn over the surface of, or bubbled through, the metal precursor contained within the vessel. The resulting evaporation of the metal precursor causes a vapor of the metal precursor to become entrained in the carrier gas to thereby produce the transition metal vapor phase reactant which can be dispensed to a reaction chamber.

In some embodiments, in addition to utilizing high purity transition metal precursors, the carrier gas may be further purified to remove unwanted impurities. Therefore, some embodiments of the disclosure may further comprise, flowing a carrier gas through a vessel containing a source of the transition metal containing vapor phase reactant to transport the transition metal containing vapor phase reactant to the reaction chamber. Further embodiments of the disclosure may comprise, flowing the carrier through a gas purifier prior to entering the source of the transition metal containing vapor phase reactant to reduce the concentration of at least one of water, or oxygen, within the carrier gas.

In some embodiments, the water concentration within the carrier gas may be reduced to less than 10 parts per million, or less than 1 part per million, or less than 100 parts per billion, or less than 10 parts per billion, or less than 1 part per billion, or even less than 100 parts per trillion.

In some embodiments, the oxygen concentration within the carrier gas may be reduced to 10 parts per million, or less than 1 part per million, or less than 100 parts per billion, or less than 10 parts per billion, or less than 1 part per billion, or even less than 100 parts per trillion.

In some embodiments, the hydrogen (H₂) concentration within the carrier gas may be reduced to less than 100 parts per trillion. In some embodiments, the carbon dioxide (CO₂) concentration within the carrier gas may be reduced to less than 100 parts per trillion. In some embodiments, the carbon monoxide (CO) concentration within the carrier gas may be reduced to less than 100 parts per trillion.

In some embodiments, the carrier gas may comprise nitrogen gas (N₂) and the carrier gas purifier may comprise a nitrogen gas purifier.

In some embodiments of the disclosure, the transition metal containing vapor phase reactant may be fed through a gas purifier prior to entering the reaction chamber in order to reduce the concentration of at least one of water, or oxygen, within the transition metal containing vapor phase reactant.

In some embodiments, the water concentration within the transition metal containing vapor phase reactant may be reduced to less than 1 atomic-%, or less than 1000 parts per million, or less than 100 parts per million, or less than 10 parts per million, or less than 1 part per million, or less than 100 parts per billion, or even less than 100 parts per trillion.

In some embodiments, the oxygen concentration within the transition metal containing vapor phase reactant may be reduced to less than 1 atomic-%, or less than 1000 parts per million, or less than 100 parts per million, or less than 10 parts per million, or less than 1 part per million, or less than 100 parts per billion, or even less than 100 parts per trillion.

Not to be bound be any theory or mechanism, but it is believed the reduction of at least one of the water concentrations, or the oxygen concentration, within the carrier gas and/or the transition metal containing vapor phase reactant may allow for the deposition of a transition metal chalcogenide film with the desired composition whilst preventing the deposition of transition metal oxide phases at an appropriate deposition temperature.

Excess transition metal vapor phase reactant, such as, for example, a hafnium precursor, or a zirconium precursor, and reaction byproducts (if any) may be removed from the substrate surface, e.g., by pumping with an inert gas. For example, in some embodiments of the disclosure the methods may include a purge cycle wherein the substrate surface is purged for a time period of less than approximately 5.0 seconds, or less than approximately 2.0 seconds, or even less than approximately 1.0 second. In some embodiments, the substrate surface is purged for a time period between about 0.01 seconds and about 60 seconds, or between about 0.05 seconds and about 10 seconds, or between about 0.1 seconds and about 5 seconds. Excess transition metal vapor phase reactant and any reaction byproducts may be removed with the aid of a vacuum generated by a pumping system.

In a second phase of the deposition cycle (“the chalcogen phase”) the substrate is contacted with a second vapor phase reactant comprising at least one chalcogen containing vapor phase reactant. In some embodiments of the disclosure, the at least one chalcogenide containing vapor reactant may comprise hydrogen sulfide (H₂S), hydrogen selenide (H₂Se), dimethyl sulfide ((CH₃)₂S), or dimethyl telluride ((CH₃)₂Te).

It will be understood by one skilled in the art that any number of chalcogen precursors may be used in the cyclical deposition processes disclosed herein. In some embodiments, a chalcogen precursor is selected from the following list: H₂S, H₂Se, H₂Te, (CH₃)₂S, (NH₄)₂S, dimethylsulfoxide ((CH₃)₂SO), (CH₃)₂Se, (CH₃)₂Te, elemental or atomic S, Se, Te, other precursors containing chalcogen-hydrogen bonds, such as H₂S₂, H₂Se₂, H₂Te₂, or chalcogenols with the formula R—Y—H, wherein R can be a substituted or unsubstituted hydrocarbon, preferably a C1-C8 alkyl or substituted alkyl, such as an alkylsilyl group, more preferably a linear or branched C1-C5 alkyl group, and Y can be S, Se, or Te. In some embodiments a chalcogen precursor is a thiol with the formula R—S—H, wherein R can be substituted or unsubstituted hydrocarbon, preferably C1-C8 alkyl group, more linear or branched preferably C1-C5 alkyl group. In some embodiments a chalcogen precursor has the formula (R₃Si)₂Y, wherein R₃Si is an alkylsilyl group and Y can be S, Se or Te. In some embodiments, a chalcogen precursor comprises S or Se. In some embodiments, a chalcogen precursor comprises S. In some embodiments, a chalcogen precursor does not comprise S. In some embodiments the chalcogen precursor may comprise an elemental chalcogen, such as elemental sulfur. In some embodiments, a chalcogen precursor does comprise Te. In some embodiments, a chalcogen precursor does not comprise Te. In some embodiments, a chalcogen precursor does comprise Se. In some embodiments, a chalcogen precursor does not comprise Se. In some embodiments, a chalcogen precursor is selected from precursors comprising S, Se or Te. In some embodiments, a chalcogen precursor comprises H₂S_(n), wherein n is from 4 to 10.

In some embodiments, suitable chalcogen precursors may include any number of chalcogen-containing compounds. In some embodiments, a chalcogen precursor may comprise at least one chalcogen-hydrogen bond. In some embodiments the chalcogen precursor may comprise a chalcogen plasma, chalcogen atoms or chalcogen radicals. In some embodiments where an energized chalcogen precursor is desired, a plasma may be generated in the reaction chamber or upstream of the reaction chamber. In some embodiments the chalcogen precursor does not comprise an energized chalcogen precursor, such as plasma, atoms or radicals. In some embodiments the chalcogen precursor may comprise a chalcogen plasma, chalcogen atoms or chalcogen radicals formed from a chalcogen precursor comprising a chalcogen-hydrogen bond, such as H₂S. In some embodiments a chalcogen precursor may comprise a chalcogen plasma, chalcogen atoms or chalcogen radicals such as a plasma comprising sulfur, selenium or tellurium, preferably a plasma comprising sulfur. In some embodiments, the plasma, atoms, or radicals comprise tellurium. In some embodiments, the plasma, atoms or radicals comprise selenium. In some embodiments the chalcogen precursor does not comprise a tellurium precursor.

In some embodiments, the purity of the chalcogen containing vapor phase reactants may influence the composition of the deposited film and therefore high purity sources of the chalcogen containing vapor phase reactant may be utilized. In some embodiments, the chalcogen containing vapor phase reactant may have a purity of greater than or equal to 99.5%. As a non-limiting example, the chalcogen containing vapor phase reactant may comprise hydrogen sulfide (H₂S) with a purity of greater than or equal to 99.5%.

In some embodiments, in addition to utilizing high purity chalcogen containing vapor phase reactants, the chalcogen precursor gas may be further purified to remove unwanted impurities. Therefore, some embodiments of the disclosure may further comprise, flowing a chalcogen containing vapor phase reactant through a gas purifier prior to entering the reaction chamber to reduce the concentration of at least one of water, or oxygen, within the chalcogen containing vapor phase reactant.

In some embodiments, the water, or oxygen concentration within the chalcogen containing vapor phase reactant may be reduced to less than 5 atomic-%, or less than 1 atomic-%, or less than 1000 parts per million, or less than 100 parts per million, or less than 10 parts per million, or less than 1 part per million, or less than 100 parts per billion, or less than 10 parts per billion, or even less than 1 part per billion.

Not to be bound be any theory or mechanism, but it is believed the reduction of at least one of the water concentration, or the oxygen concentration within the chalcogen containing vapor phase reactant may allow for the deposition of transition metal chalcogenide film with the desired composition whilst preventing the deposition of transition metal oxide phases at an appropriate deposition temperature.

In some embodiments, exposing the substrate to the chalcogen containing vapor phase reactant may comprise, pulsing the chalcogen precursor (e.g., hydrogen sulfide) over the substrate for a time period of between 0.1 seconds and 2.0 seconds, or from about 0.01 seconds to about 10 seconds, or less than about 20 seconds, or less than about 10 seconds, or less than about 5 seconds. During the pulsing of the chalcogen precursor over the substrate the flow rate of the chalcogen precursor may be less than 2000 sccm, or less than 500 sccm, or even less than 100 sccm. In addition, during the pulsing of the chalcogen precursor over the substrate the flow rate of the chalcogen precursor may be from about 1 sccm to about 2000 sccm, or from about 5 sccm to about 1000 sccm, or from about 10 sccm to about 500 sccm.

The second vapor phase reactant comprising a chalcogen containing precursor may react with the metal-containing molecules left on the substrate. In some embodiments, the second phase chalcogen precursor may comprise hydrogen sulfide and the reaction may deposit a transition metal disulfide on the surface of the substrate.

Excess second source chemical and reaction byproducts, if any, may be removed from the substrate surface, for example, by a purging gas pulse and/or vacuum generated by a pumping system. Purging gas is preferably any inert gas, such as, without limitation, argon (Ar), nitrogen (N₂), or helium (He). A phase is generally considered to immediately follow another phase if a purge (i.e., purging gas pulse) or other reactant removal step intervenes.

The deposition cycle in which the substrate is alternatively contacted with the first vapor phase reactant (i.e., the transition metal containing precursor) and the second vapor phase reactant (i.e., the chalcogen containing precursor) may be repeated one or more times until a desired thickness of a transition metal chalcogenide is deposited. It should be appreciated that in some embodiments of the disclosure, the order of the contacting of the substrate with the first vapor phase reactant and the second vapor phase reactant may be such that the substrate is first contacted with the second vapor phase reactant followed by the first vapor phase reactant. In addition, in some embodiments, the cyclical deposition process may comprise contacting the substrate with the first vapor phase reactant (i.e. the transition metal containing precursor) one or more times prior to contacting the substrate with the second vapor phase reactant (i.e., the chalcogen containing precursor) one or more times and similarly may alternatively comprise contacting the substrate with the second vapor phase reactant one or more times prior to contacting the substrate with the first vapor phase reactant one or more times.

In addition, some embodiments of the disclosure may comprise non-plasma reactants, e.g., the first and second vapor phase reactants are substantially free of ionized reactive species. In some embodiments, the first and second vapor phase reactants are substantially free of ionized reactive species, excited species or radical species. For example, both the first vapor phase reactant and the second vapor phase reactant may comprise non-plasma reactants to prevent ionization damage to the underlying substrate and the associated defects thereby created.

The cyclical deposition processes described herein, utilizing a transition metal containing precursor and a chalcogen containing precursor to form a transition metal chalcogenide film, may be performed in an ALD or CVD deposition system with a heated substrate, i.e., the temperature of the substrate during the process of contacting the substrate with the chemical precursors may be controlled.

For example, in some embodiments, methods may comprise heating the substrate to temperature of between approximately 200° C. and approximately 500° C., or even heating the substrate to a temperature of between approximately 350° C. and approximately 450° C. Of course, the appropriate temperature window for any given cyclical deposition process, such as for an ALD reaction, will depend upon the surface termination and reactant species involved. Here, the temperature varies depending on the precursors being used and is generally at or below about 700° C. In some embodiments, the deposition temperature is generally at or above about 100° C. for vapor deposition processes. In some embodiments the deposition temperature is between about 100° C. and about 600° C., and in some embodiments the deposition temperature is between about 300° C. and about 500° C. In some embodiments the deposition temperature is below about 500° C., or below about 475° C., or below about 450° C., or below about 425° C. or below about 400° C., or below about 375° C., or below about 350° C., or below about 325° C. or below about 300° C. In some instances the deposition temperature can be below about 250° C., or below about 200° C., or below about 150° C., or below about 100° C., for example, if additional reactants or reducing agents are used in the process. In some instances the deposition temperature can be above about 20° C., above about 50° C. and above about 75° C. In some embodiments of the disclosure, the deposition temperature, i.e., the temperature of the substrate during deposition is approximately 400° C.

In some embodiments the growth rate of the transition metal chalcogenide film is from about 0.005 Å/cycle to about 5 Å/cycle, or from about 0.01 Å/cycle to about 2.0 Å/cycle. In some embodiments the growth rate of the film is more than about 0.05 Å/cycle, or more than about 0.1 Å/cycle, or more than about 0.15 Å/cycle, or more than about 0.20 Å/cycle, or more than about 0.25 Å/cycle, or even more than about 0.3 Å/cycle. In some embodiments the growth rate of the film is less than about 2.0 Å/cycle, or less than about 1.0 Å/cycle, or less than about 0.75 Å/cycle, or less than about 0.5 Å/cycle, or less than about 0.2 Å/cycle. In some embodiments of the disclosure, the growth rate of the transition metal chalcogenide is approximately 0.10 Å/cycle.

The embodiments of the disclosure may comprise a cyclical deposition process which may be illustrated in more detail by the exemplary method 100 of FIG. 1. The exemplary method 100 may begin with a process block 110 which comprises, providing a substrate into a reaction chamber and heating the substrate to the deposition temperature.

In some embodiments of the disclosure, the substrate may comprise a planar substrate or a patterned substrate including high aspect ratio features, such as, for example, trench structures and/or fin structures. The substrate may comprise one or more materials including, but not limited to, silicon (Si), germanium (Ge), germanium tin (GeSn), silicon germanium (SiGe), silicon germanium tin (SiGeSn), silicon carbide (SiC), or a group III-V semiconductor material, such as, for example, gallium arsenide (GaAs), gallium phosphide (GaP), or gallium nitride (GaN). In some embodiments, the substrate may comprise one or more dielectric materials including, but not limited to, oxides, nitrides, or oxynitrides. For example, the substrate may comprise a silicon oxide (e.g., SiO₂), a metal oxide (e.g., Al₂O₃), a silicon nitride (e.g., Si₃N₄), or a silicon oxynitride. In some embodiments of the disclosure, the substrate may comprise an engineered substrate wherein a surface semiconductor layer is disposed over a bulk support with an intervening buried oxide (BOX) disposed there between.

Patterned substrates may comprise substrates that may include semiconductor device structures formed into or onto a surface of the substrate, for example, a patterned substrate may comprise partially fabricated semiconductor device structures, such as, for example, transistors and/or memory elements. In some embodiments, the substrate may contain monocrystalline surfaces and/or one or more secondary surfaces that may comprise a non-monocrystalline surface, such as a polycrystalline surface and/or an amorphous surface. Monocrystalline surfaces may comprise, for example, one or more of silicon (Si), silicon germanium (SiGe), germanium tin (GeSn), germanium (Ge), or a III-V material. Polycrystalline or amorphous surfaces may include dielectric materials, such as oxides, oxynitrides, or nitrides, such as, for example, silicon oxides and silicon nitrides.

The reaction chamber utilized for the exemplary cyclical deposition process 100 may be an atomic layer deposition reaction chamber, or a chemical vapor deposition reaction chamber, or any of the reaction chambers as previously described herein. In some embodiments of the disclosure, the reaction chamber may be subjected to a pre-annealing process prior to loading the substrate within the reaction chamber or with the substrate pre-loaded into the reaction chamber. For example, the pre-annealing process may be utilized to reduce the concentration of at least one of water, and/or oxygen, within the reaction chamber. Therefore, some embodiments of the disclosure may further comprise, pre-annealing the reaction chamber prior to film deposition at temperature of greater than 400° C., or greater than 500° C., or greater than 600° C., or even greater than 700° C. In some embodiments, the pre-annealing of the reaction chamber at high temperature may be performed for time period of less than 60 minutes, or less than 30 minutes, or less than 15 minutes, or less than 10 minutes, or even less than 5 minutes.

The process block 110 (of FIG. 1) may continue by heating the substrate to a desired deposition temperature, as previously disclosed herein. As a non-limiting example, the substrate may be heated to deposition temperature between approximately 300° C. and approximately 450° C., or to a temperature of approximately 400° C.

The exemplary method 100 may continue with cyclical deposition phase 140 which may commence by means of a process block 120 which comprises, contacting the substrate with a transition metal containing vapor phase reactant, as previously disclosed herein. As a non-limiting example, the substrate may be contacted with hafnium tetrachloride (HfCl₄) or zirconium tetrachloride (ZrCl₄), for a time period of approximately 1 second. Upon contacting the substrate with the transition metal containing precursor, the excess transition metal containing precursor and any byproducts may be removed from the reaction chamber by a purge/pump process.

The cyclical deposition phase 140 of the exemplary method 100 may continue by means of a process block 130 which comprises, contacting the substrate with a chalcogen containing vapor phase reactant, as previously disclosed herein. As a non-limiting example, the substrate may be contacted with hydrogen sulfide (H₂S) for a time period of approximately 1 second. Upon contacting the substrate with the chalcogen containing precursor, the excess chalcogen containing precursor and any byproducts may be removed from the reaction chamber by purge/pump process.

The method wherein the substrate is alternately and sequentially contacted with at least one transition metal containing vapor phase reactant and contacted with at least one chalcogen containing vapor phase reactant may constitute one unit deposition cycle. For example, a unit deposition cycle may comprise, contacting substrate with the transition metal vapor phase reactant, purging the reaction chamber, contacting the substrate with the chalcogen containing vapor phase reactant, and again purging the reaction chamber.

In some embodiments of the disclosure, the method of depositing a transition metal chalcogenide may comprise repeating the unit deposition cycle one or more times. For example, the cyclic deposition phase 140 of exemplary method 100 may continue by means of a decision gate 150 which determines if the cyclical deposition phase 140 of exemplary method 100 continues or exits. The decision gate of the process block 150 may be determined based on the thickness of the transition metal chalcogenide film deposited. For example, if the thickness of the transition metal chalcogenide film is insufficient for the desired application, then the cyclical deposition phase 140 of the exemplary method 100 may return to the process block 120 and the processes of contacting the substrate with a transition metal containing vapor phase reactant and contacting the substrate with a chalcogen containing vapor phase reactant may be repeated one or more times. Once the transition metal chalcogenide film has been deposited to a desired thickness the exemplary method 100 may exit via a process block 160 and the transition metal chalcogenide film may be subjected to additional processes to form a device structure.

In some embodiments of the disclosure, the deposition temperature of the transition metal chalcogenide film may affect the growth rate of the chalcogenide film, the crystallinity of the chalcogenide film, and the composition the chalcogenide film. As a non-limiting example, FIG. 2 illustrates the growth rate, crystallinity, and composition, of exemplary hafnium disulfide films deposited at various deposition temperatures utilizing hafnium tetrachloride (HfCl₄) and hydrogen sulfide (H₂S) as the precursor chemicals. Examination of FIG. 2 illustrates that between a deposition temperature of approximately 200° C., up to a deposition of approximately 350° C., the deposition rate of the exemplary hafnium disulfide films decreases and the crystal structure of the hafnium disulfide films is amorphous, i.e., there is no long range ordering of the crystal structure which would normally be associated with a crystalline material. Between a deposition temperature of approximately 350° C. and approximately 400° C. there is an increase the growth rate of the exemplary hafnium disulfide films and the crystal structure of the hafnium disulfide films becomes crystalline, i.e., there is long range ordering of the crystalline structure of the chalcogenide film. In addition, between a deposition temperature of approximately 350° C. and approximately 400° C., the exemplary hafnium disulfide film exhibits a composition of hafnium disulfide (HfS₂). However, as the deposition temperature is further increased above a temperature of approximately 400° C., the growth rate of the exemplary films again decreases and the composition of the deposited film becomes that of a mixture between a hafnium sulfide and a hafnium oxide. The deposition of hafnium oxide phases above a temperature of approximately 400° C. may result from residual oxygen and/or water remaining in the reaction chamber utilized in the above non-limiting examples. In further non-limiting examples, the residual oxygen and/or water concentration within the reaction chamber may be further reduced and deposition above a temperature of approximately 400° C. may result in deposition of a hafnium disulfide (HfS₂) film without the deposition of hafnium oxide phases.

Therefore, in some embodiments of the disclosure, the transition metal chalcogenide film may comprise a hafnium sulfide and particularly hafnium disulfide (HfS₂). In addition, in some embodiments, the transition metal chalcogenide film may be crystalline with a composition comprising hafnium disulfide (HfS₂) at a deposition temperature between approximately 350° C. and approximately 400° C., and particular at a deposition temperature of approximately 400° C. In some embodiments, a crystalline hafnium disulfide (HfS₂) film may be deposited at a deposition temperature greater than 400° C.

As a further non-limiting example, FIG. 3 illustrates the growth rate, crystallinity, and composition, of exemplary zirconium sulfide films deposited at various deposition temperatures utilizing zirconium tetrachloride (ZrCl₄) and hydrogen sulfide (H₂S) as the precursor chemicals. Examination of FIG. 3 illustrates that between a deposition temperature of approximately 200° C., up to a deposition of approximately 350° C., the deposition rate of the exemplary zirconium sulfide films increases and the crystal structure of the zirconium sulfide films is amorphous, i.e., there is no long range ordering in the crystal structure which would normally be associated with a crystalline material. Between a deposition temperature of approximately 350° C. and approximately 400° C. there is a further increase in the growth rate of the exemplary zirconium sulfide films and the crystal structure of the zirconium sulfide films becomes crystalline, i.e., there is long range ordering of the crystalline structure of the chalcogenide film. In addition, between a deposition temperature of approximately 350° C. and approximately 400° C., the exemplary zirconium sulfide film exhibits a composition of zirconium disulfide (ZrS₂). However, as the deposition temperature is further increased above a temperature of approximately 400° C., the growth rate of the exemplary films initially decreases and then again increases and the composition of the deposited film becomes that of a mixture between a zirconium sulfide and a zirconium oxide. The deposition of zirconium oxide phases above a temperature of approximately 400° C. may result from residual oxygen and/or water remaining in the reaction chamber utilized in the above non-limiting examples. In further non-limiting examples, the residual oxygen and/or water concentration within the reaction chamber may be further reduced and deposition above a temperature of approximately 400° C. may result in deposition of a zirconium disulfide (ZrS₂) film without the deposition of zirconium oxide phases.

Therefore, in some embodiments of the disclosure, the transition metal chalcogenide film may comprise a zirconium sulfide and particularly zirconium disulfide (ZrS₂). In addition, in some embodiments, the transition metal chalcogenide film may be crystalline with a composition comprising zirconium disulfide (ZrS₂) at a deposition temperature between approximately 350° C. and approximately 400° C., and particular at a deposition temperature of approximately 400° C. In some embodiments, a crystalline zirconium disulfide (ZrS₂) film may be deposited at a deposition temperature greater than 400° C.

As further non-limiting examples of the transition metal chalcogenide films deposited according to the embodiments of the disclosure, FIG. 4 and FIG. 5 illustrate grazing incidence x-ray diffraction (GIXRD) data for hafnium sulfide films deposited utilizing hafnium tetrachloride (HfCl₄) and hydrogen sulfide (H₂S) as chemical precursor (FIG. 4) and zirconium sulfide films deposited utilizing zirconium tetrachloride (ZrCl₄) and hydrogen sulfide (H₂S) as chemical precursors (FIG. 5) deposited at various deposition temperature between 200° C. and 500° C.

Examination of FIG. 4 illustrates that for a deposition temperature of 200° C., up to a deposition temperature of 350° C., the GIXRD data does not include any discernable peaks in the data, corresponding to a non-crystalline film, i.e., the exemplary hafnium sulfide films are amorphous. For a deposition temperature of 400° C., up to a deposition temperature of 450° C., the GIXRD data has a discernable primary peak corresponding to a crystalline hafnium sulfide film and in particular a hafnium disulfide film with a composition (HfS₂). In addition, for a deposition temperature between 400° C. and 450° C. the exemplary hafnium disulfide films have a predominate (001) crystallographic orientation as demonstrated by the location of the peak in the GIXRD data. For a deposition temperature of 500° C. the peak in the GIXRD data related to hafnium disulfide is not discernable but rather a number of smaller peaks corresponding to a hafnium oxide (e.g., HfO₂) are present indicating the deposited film comprises a hafnium oxide film. As previously described herein, the presence of hafnium oxide phases at a deposition of 500° C. may be due to residual water and/or oxygen within the reaction chamber utilized to deposit the exemplary hafnium sulfide films of FIG. 4. In additional non-limiting examples, the reaction chamber utilized to deposit the hafnium sulfide films may have a reduced concentration of water and/or oxygen and deposition at a temperature of 500° C. and above may result in crystalline hafnium sulfide films without the presence of hafnium oxide phases.

Therefore, in some embodiments of the disclosure, the transition metal chalcogenide film may comprise a hafnium sulfide and particularly hafnium disulfide (HfS₂). In addition, in some embodiments, the transition metal chalcogenide film may comprise crystalline hafnium disulfide (HfS₂) with a predominant (001) crystallographic orientation for a deposition temperature between approximately 350° C. and approximately 400° C., and particular at a deposition temperature of approximately 400° C. In some embodiments, the transition metal chalcogenide film may comprise crystalline hafnium disulfide (HfS₂) with a predominant (001) crystallographic orientation for a deposition temperature greater than 400° C.

In addition, GIXRD data from exemplary zirconium sulfide films are illustrated in FIG. 5 and examination of FIG. 5 illustrates that for a deposition temperature of 200° C., up to a deposition temperature of 300° C., the GIXRD data does not include any discernable peaks in the data, corresponding to a non-crystalline film, i.e., the exemplary zirconium sulfide films are amorphous. For a deposition temperature of 350° C., up to a deposition temperature of 450° C., the GIXRD data has a single discernable peak corresponding to a crystalline zirconium sulfide film and in particular a zirconium disulfide film with a composition (ZrS₂). In addition, for a deposition temperature between 350° C. and 450° C. the exemplary zirconium disulfide films have a predominate (001) crystallographic orientation as demonstrated by the location of the peak in the GIXRD data. For a deposition temperature of 500° C. the peak in the GIXRD data related to zirconium disulfide is present but also a number of smaller peaks corresponding to a zirconium oxide (e.g., ZrO₂) are present indicating the deposited film comprises a mixture of both a zirconium sulfide and a zirconium oxide. As previously described herein, the presence of zirconium oxide phases at a deposition temperature of 500° C. may be due to residual water and/or oxygen within the reaction chamber utilized to deposit the exemplary zirconium sulfide films of FIG. 5. In additional non-limiting examples, the reaction chamber utilized to deposit the zirconium sulfide films may have a reduced concentration of water and/or oxygen and deposition at a temperature of 500° C. and above may result in crystalline zirconium sulfide films without the presence of zirconium oxide phases.

Therefore, in some embodiments of the disclosure, the transition metal chalcogenide film may comprise a zirconium sulfide and a particularly zirconium disulfide (ZrS₂). In addition, in some embodiments, the transition metal chalcogenide film may comprise crystalline zirconium disulfide (ZrS₂) with a (001) crystallographic orientation for a deposition temperature between approximately 300° C. and approximately 450° C., and particular at a deposition temperature of approximately 400° C. In some embodiments, the transition metal chalcogenide film may comprise crystalline zirconium disulfide (ZrS₂) with a predominant (001) crystallographic orientation for a deposition temperature of greater than 400° C.

In some embodiments of the disclosure, the as-deposited transition metal chalcogenide films may be subjected to a post-deposition annealing process to improve the crystallinity of the transition metal chalcogenide thin films. For example, in some embodiments, the method of depositing the transition metal chalcogenide film may further comprise, a post-deposition annealing of the metal chalcogenide at a temperature above the deposition temperature of the transition metal chalcogenide film. For example, in some embodiments, annealing of the transition metal chalcogenide may comprise, heating the transition metal chalcogenide film to a temperature of approximately less than 800° C., or approximately less than 600° C., or approximately less than 500° C., or even approximately less than 400° C. In some embodiments, the post-deposition annealing of the transition metal chalcogenide thin film may be performed in an atmosphere comprising a chalcogen, for example, the post-deposition annealing process may be performed in an ambient comprising a chalcogenide compound, for example sulfur compounds, such as a hydrogen sulfide (H₂S) atmosphere. In some embodiments, the post-deposition annealing of the metal chalcogenide thin film may be performed for a time period of less than 1 hour, or less than 30 minutes, or less than 15 minutes, or even less than 5 minutes. In some embodiments, the post-deposition annealing of the transition metal chalcogenide thin film may be performed in an atmosphere not comprising chalcogens, such as S, Se, or Te, for example, in inert gas ambient such as N₂, or noble gas, such as Ar or He, or in hydrogen containing ambient such as H₂ or H₂/N₂ ambient.

Transition metal chalcogenide films, such as, for example, hafnium disulfide and zirconium disulfide films, deposited according to some of the embodiments of the disclosure may be continuous films comprising a 2D material. In some embodiments the films comprising a transition metal chalcogenide film deposited according to some of the embodiments disclosure may be continuous at a thickness below about 100 nanometers, or below about 60 nanometers, or below about 50 nanometers, or below about 40 nanometers, or below about 30 nanometers, or below about 25 nanometers, or below about 20 nanometers, or below about 15 nanometers, or below about 10 nanometers, or below about 5 nanometers or lower.

In some embodiments, the transition metal chalcogenide films deposited according to the embodiments of the disclosure may be continuous over a substrate having a diameter greater than 100 millimeters, or greater than 200 millimeters, or greater than 300 millimeters, or even greater than 400 millimeters. The continuity referred to herein can be physical continuity or electrical continuity. In some embodiments the thickness at which a film may be physically continuous may not be the same as the thickness at which a film is electrically continuous, and the thickness at which a film may be electrically continuous may not be the same as the thickness at which a film is physically continuous.

In some embodiments of the disclosure, the transition metal chalcogenide films deposited by the methods disclosed herein may comprise at least one of a hafnium sulfide, a hafnium selenide, a hafnium telluride, a zirconium sulfide, a zirconium selenide, or a zirconium telluride.

In some embodiments of the disclosure, the transition metal chalcogenide films deposited by the methods disclosed herein may comprise a hafnium chalcogenide and particularly a hafnium sulfide having the general formula HfS_(x), wherein x may range from approximately 0.75 to approximately 2.8, or wherein x may range from approximately 0.8 to approximately 2.5, or wherein x may range from 0.9 to approximately 2.3, or alternatively wherein x may range from approximately 0.95 to approximately 2.2. The elemental composition ranges for HfS_(x) may comprise Hf from about 30 atomic % to about 60 atomic %, or from about 35 atomic % to about 55 atomic %, or even from about 40 atomic % to about 50 atomic %. Alternatively the elemental composition ranges for HfS_(x) may comprise S from about 25 atomic % to about 75 atomic %, or S from about 30 atomic % to about 60 atomic %, or even S from about 35 atomic % to about 55 atomic %.

In some embodiments of the disclosure, the transition metal chalcogenide films deposited by the methods disclosed herein may comprise a zirconium chalcogenide and particularly a zirconium sulfide having the general formula ZrS_(x), wherein x may range from approximately 0.75 to approximately 2.8, or wherein x may range from approximately 0.8 to approximately 2.5, or wherein x may range from 0.9 to approximately 2.3, or alternatively wherein x may range from approximately 0.95 to approximately 2.2. The elemental composition ranges for ZrS_(x) may comprise Zr from about 30 atomic % to about 60 atomic %, or from about 35 atomic % to about 55 atomic %, or even from about 40 atomic % to about 50 atomic %. Alternatively the elemental composition ranges for ZrS_(x) may comprise S from about 25 atomic % to about 75 atomic %, or S from about 30 atomic % to about 60 atomic %, or even S from about 35 atomic % to about 55 atomic %.

In additional embodiments, the transition metal chalcogenide films of the present disclosure may comprise, less than about 20 atomic % oxygen, or less than about 10 atomic % oxygen, or less than about 5 atomic % oxygen, or even less than about 2 atomic % oxygen. In further embodiments, the transition metal chalcogenide films may comprise, less than about 25 atomic % hydrogen, or less than about 10 atomic % hydrogen, or less than about 5 atomic % of hydrogen, or less than about 2 atomic % of hydrogen, or even less than about 1 atomic % of hydrogen. In yet further embodiments, the transition metal chalcogenide films may comprise, less than about 20 atomic % carbon, or less than about 10 atomic % carbon, or less than about 5 atomic % carbon, or less than about 2 atomic % carbon, or less than about 1 atomic % of carbon, or even less than about 0.5 atomic % carbon. In the embodiments outlined herein, the atomic concentration of an element may be determined utilizing Rutherford backscattering (RBS) and/or elastic recoil detection analysis (ERDA).

In some embodiments of the disclosure, the transition metal chalcogenide films may be deposited on a three-dimensional structure. In some embodiments, the step coverage of the transition metal chalcogenide films may be equal to or greater than about 50%, or greater than about 80%, or greater than about 90%, or about 95%, or about 98%, or about 99% or greater in structures having aspect ratios (height/width) of more than about 2, more than about 5, more than about 10, more than about 25, more than about 50, or even more than about 100.

In some embodiments, the transition metal chalcogenide film of the present disclosure, such as hafnium and zirconium dichalcogenide films, may be deposited to a thickness from about 20 nanometers to about 100 nanometers. In some embodiments, a transition metal chalcogenide thin film deposited according to some of the embodiments described herein may have a thickness from about 20 nanometers to about 60 nanometers. In some embodiments, a transition metal chalcogenide thin film deposited according to some of the embodiments described herein may have a thickness greater than about 20 nanometers, or greater than about 30 nanometers, or greater than about 40 nanometers, or greater than about 50 nanometers, or greater than about 60 nanometers, or greater than about 100 nanometers, or greater than about 250 nanometers, or greater than about 500 nanometers, or even greater. In some embodiments a transition metal chalcogenide thin film deposited according to some of the embodiments described herein may have a thickness of less than about 50 nanometers, or less than about 30 nanometers, or less than about 20 nanometers, or less than about 15 nanometers, or less than about 10 nanometers, or less than about 5 nanometers, or less than about 3 nanometers, or less than about 2 nanometers, or less than about 1.5 nanometers, or even less than about 1 nanometer.

In some embodiments a transition metal chalcogenide film, such as a hafnium or zirconium dichalcogenide film deposited according to some of the embodiments described herein may have a thickness of equal to or less than about 10 monolayers of transition metal chalcogenide material, or equal to or less than about 7 monolayers of transition metal chalcogenide material, or equal to or less than about 5 monolayers of transition metal chalcogenide material, or to equal or less than about 4 monolayers of transition metal chalcogenide material, or equal to or less than about 3 monolayers of transition metal chalcogenide material, or equal to or less than about 2 monolayers of transition metal chalcogenide material, or even equal to or less than about 1 monolayer of transition metal chalcogenide material.

In some embodiments of the disclosure, the transition metal chalcogenide films deposited according the methods disclosed herein may include a protective capping layer to substantially prevent, or even prevent, the unwanted oxidation of the transition metal chalcogenide film. For example, upon completion of the deposition of the transition metal chalcogenide the chalcogenide film may be unloaded from the reaction chamber and exposed to ambient conditions wherein oxygen and/or water within the ambient environment may oxidize the deposited transition metal chalcogenide film.

Therefore, in some embodiments, a capping layer may be deposited over the transition metal chalcogenide film and particularly deposited directly over the transition metal chalcogenide film. In addition, to prevent any potential oxidation of the transition metal chalcogenide film, the capping layer may be deposited within the same reaction chamber utilized to deposit the transition metal chalcogenide, i.e., the capping layer may be deposited in-situ within the same reaction chamber utilized to deposit the transition metal chalcogenide film. Therefore, in some embodiments of the disclosure, the methods may further comprise, in-situ depositing a capping layer over the transition metal chalcogenide film to substantially prevent oxidation of the transition metal chalcogenide film when exposed to ambient conditions.

In some embodiments, the capping layer may comprise a metal silicate film. In some embodiments, the metal silicate film may comprise at least one of an aluminum silicate (Al_(x)Si_(y)O_(x)), a hafnium silicate (Hf_(x)Si_(y)O_(x)), or a zirconium silicate (Zr_(x)Si_(y)O_(x)). More detailed information regarding the deposition of metal silicate films may be found in U.S. Pat. No. 6,632,279, filed on Oct. 13, 2000, titled “METHOD FOR GROWING THIN OXIDE FILMS,” all of which is hereby incorporated by reference and made a part of this specification.

In some embodiments, the capping layer may be deposited directly on the transition metal chalcogenide film by a cyclical deposition process, such as an atomic layer deposition process, or a cyclical chemical vapor deposition process, as disclosed herein previously. As a non-limiting example, the capping layer may comprise a metal silicate and the metal silicate may be deposited by cyclical deposition process, such as atomic layer deposition, for example. In some embodiments, the capping layer may be deposited using processes comprising non-oxidative reactants/precursors, or non-oxygen reactants (for example without O₂, H₂O, O₃, H₂O₂, O-containing plasmas, radicals or atoms) containing processes. Therefore, in some embodiments, the capping layer may be deposited without utilizing H₂O, O₃, or H₂O₂. In some embodiments, the capping layer may be deposited without utilizing an oxygen based plasma, i.e., without 0-containing plasmas, oxygen radicals, oxygen atoms, or oxygen excited species. The capping layer may be deposited using processes comprising non-oxidative reactants/precursor, or non-oxygen reactants to prevent, or substantially prevent, the oxidation of the underlying transition metal chalcogenide film. Therefore, in some embodiments, in-situ depositing a capping layer over the transition metal chalcogenide film may be performed without additional oxidation of the transition metal chalcogenide film.

In other embodiments, the capping layer may comprise a metal, such as a transition metal, for example. In some embodiments, the capping layer may comprise, a nitride, a sulfide, a carbide, or mixtures thereof, or for example a silicon containing layer such as an amorphous silicon layer. In other embodiments, the capping layer can be a dielectric layer. In other embodiments, the capping layer can be a conductive layer. In other embodiments, the capping layer can be a semiconductor layer.

An exemplary ALD process for depositing the capping layer may comprise one or more repeated unit deposition cycles, wherein a unit deposition cycle may comprise, contacting the substrate with a metal vapor phase reactant, purging the reaction chamber of excess metal precursor and reaction by-products, contacting the substrate with a precursor comprising both a silicon component and an oxygen component, and purging the reaction chamber for a second time. As a non-limiting example, the capping layer may comprise an aluminum silicate film (Al_(x)Si_(y)O_(z)) and the metal vapor phase reactant may comprise aluminum trichloride (AlCl₃) whereas the precursor comprising both a silicon component and an oxygen component may comprise tetra-n-butoxysilane Si(O^(n)Bu)₄. In some embodiments of the disclosure, the capping layer may comprise a metal silicate deposited without the use of an oxidizing precursor, such as, for example, O₂, H₂O, O₃, H₂O₂, O-containing plasmas, radicals or atoms.

In some embodiments, the capping layer may be deposited at the same temperature utilized to deposit the transition metal chalcogenide film. For example, the capping layer may be deposited at a temperature of less than 500° C., or less than 450° C., or less than 400° C., or less than 300° C., or less than 200° C. In some embodiments, the capping layer may be deposited at a temperature between approximately 200° C. and 500° C., and particularly at a deposition temperature of approximately 400° C.

In some embodiments, the capping layer may be deposited to a thickness of less than 50 nanometers, or less than 40 nanometers, or less than 30 nanometers, or less than 20 nanometers, or less than 10 nanometers, or less than 7 nanometers, or less than 5 nanometers, or less than 3 nanometers, or less than 2 nanometers, or even less than 1 nanometer. In some embodiments, the capping layer is a continuous film and is disposed directly over the metal chalcogenide film to substantially prevent oxidation of the metal chalcogenide film.

As a non-limiting example, FIG. 6 illustrates the ambient stability over time of both a bare zirconium chalcogenide film and a zirconium chalcogenide film capped with an aluminum silicate capping layer deposited according to the embodiments of the disclosure. In more detail, FIG. 6 illustrates the change in the normalized x-ray diffraction (XRD) intensity of the primary (001) peak over exposure time to ambient conditions for both an aluminum silicate capped zirconium disulfide film (represented by the triangular data markers) and an uncapped, bare zirconium disulfide film (represented by the square data marks). Examination of the data for the bare zirconium disulfide film illustrates that the intensity of the (001) peak in the XRD data decreases over time indicating the bare zirconium disulfide oxidizes over the time exposed to the ambient conditions. In contrast, examination of the data for the aluminum silicate capped zirconium disulfide film illustrates no decrease in the intensity of the (001) peak in the XRD data over time, indicating substantially no oxidation of the capped zirconium disulfide film.

In some embodiments of the disclosure, the in-situ deposition of the capping layer directly on the surface of the transition metal chalcogenide film may be beneficial in improving the quality of thin transition metal chalcogenide films as the capping layer may prevent oxidation of the chalcogenide film during reaction chamber cool down after the deposition.

In more detail, FIG. 7A illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary zirconium disulfide films deposited utilizing a different number of deposition cycles without a capping layer and FIG. 7B illustrates grazing incidence x-ray diffraction (GIXRD) data for exemplary zirconium chalcogenide films deposited utilizing a different number of deposition cycles with an in-situ capping layer deposited directly over the chalcogenide film. Examination of FIG. 7A, i.e., the uncapped zirconium disulfide, illustrates that the XRD peak corresponding to crystalline zirconium disulfide does not appear until 1000 deposition cycle have been completed, which corresponds to a thickness of approximately 8 nanometers. In contrast, examination of FIG. 7B, i.e., the capped zirconium disulfide, illustrates that the XRD peak corresponding to crystalline zirconium disulfide appears at 500 deposition cycles, which corresponds to a thickness of approximately 4 nanometers. Therefore, in some embodiments of the disclosure, the metal chalcogenide film may be covered by an in-situ capping layer and the metal chalcogenide film may be crystalline below a thickness of less than approximately 5 nanometers, or less than approximately 4 nanometers, or less than approximately 2 nanometers, or less than 1.5 nanometers, or even less than 1 nanometer.

The metal chalcogenide films deposited by the cyclical deposition processes disclosed herein may be utilized in a variety of contexts, such as in the formation of semiconductor device structures. One of skill in the art will recognize that the processes described herein are applicable to many contexts, including, but not limited to, the fabrication of transistors.

As a non-limiting example, and with reference to FIG. 8, a semiconductor device structure 800 may comprise a field effect transistor (FET) which may include a silicon substrate 802 and a silicon dioxide (SiO₂) layer 804 disposed over the silicon substrate 802. The semiconductor device structure 800 may further comprise a source region 806 and a drain region 808. Disposed between the source and drain regions is a transition metal chalcogenide film 810 deposited according to the embodiments of the disclosure. The transition metal chalcogenide film 810 may comprise a film of hafnium disulfide or zirconium disulfide and may consist of the channel region of the FET structure. In some embodiments of the disclosure, the transition metal chalcogenide film 810 may have thickness of less than 10 nanometers, or less than 5 nanometers, or even less than 1 nanometer. Disposed directly over the transition metal chalcogenide film 810 may be a capping layer 811. For example, the capping layer 811 may comprise a metal silicate film and in particular an aluminum silicate film. The semiconductor device structure 800 may further comprise a gate dielectric layer 812 disposed over the transition metal chalcogenide film 810, wherein the gate dielectric layer 812 may comprise hafnium dioxide (HfO₂). The semiconductor device structure 800 may further comprise a gate electrode 814 disposed over the transition metal chalcogenide film 810.

Embodiments of the disclosure may also include a reaction system configured for depositing the transition metal chalcogenide films of the present disclosure. In more detail, FIG. 9 schematically illustrates a reaction system 900 including a reaction chamber 902 that further includes mechanism for retaining a substrate (not shown) under predetermined pressure, temperature, and ambient conditions, and for selectively exposing the substrate to various gases. A precursor reactant source 904 may be coupled by conduits or other appropriate means 904A to the reaction chamber 902, and may further couple to a manifold, valve control system, mass flow control system, or mechanism to control a gaseous precursor originating from the precursor reactant source 904. A precursor (not shown) supplied by the precursor reactant source 904, the reactant (not shown), may be liquid or solid under room temperature and standard atmospheric pressure conditions. Such a precursor may be vaporized within a reactant source vacuum vessel, which may be maintained at or above a vaporizing temperature within a precursor source chamber. In such embodiments, the vaporized precursor may be transported with a carrier gas (e.g., an inactive or inert gas) and then fed into the reaction chamber 902 through conduit 904A. In other embodiments, the precursor may be a vapor under standard conditions. In such embodiments, the precursor does not need to be vaporized and may not require a carrier gas. For example, in one embodiment the precursor may be stored in a gas cylinder. The conduit 904A may further comprise a gas purifier 905A for substantially removing unwanted contaminants from the vapor fed to the reaction chamber 902.

The reaction system 900 may also include additional precursor reactant sources, such as precursor reactant source 906 which may also be coupled to the reaction chamber 902 by mean of conduits 906A and additional gas purifier 905B, as described above.

A purge gas source 908 may also be coupled to the reaction chamber 902 via conduits 908A, and selectively supplies various inert or noble gases to the reaction chamber 902 to assist with the removal of precursor gas or waste gasses from the reaction chamber. The various inert or noble gasses that may be supplied may originate from a solid, liquid or stored gaseous form.

The reaction system 900 of FIG. 9 may also comprise a system operation and control mechanism 910 that provides electronic circuitry and mechanical components to selectively operate valves, manifolds, pumps and other equipment included in the reaction system 900. Such circuitry and components operate to introduce precursors, purge gasses from the respective precursor sources 904, 906, and purge gas source 908. The system operation and control mechanism 910 also controls timing of gas pulse sequences, temperature of the substrate and reaction chamber, and pressure of the reaction chamber and various other operations necessary to provide proper operation of the reaction system 900. The operation and control mechanism 910 can include control software and electrically or pneumatically controlled valves to control flow of precursors, reactants and purge gasses into and out of the reaction chamber 902. The control system can include modules such as a software or hardware component, e.g., a FPGA or ASIC, which performs certain tasks. A module can advantageously be configured to reside on the addressable storage medium of the control system and be configured to execute one or more processes.

Those of skill in the relevant arts appreciate that other configurations of the present reaction system are possible, including different number and kind of precursor reactant sources and purge gas sources. Further, such persons will also appreciate that there are many arrangements of valves, conduits, precursor sources, purge gas sources that may be used to accomplish the goal of selectively feeding gasses into reaction chamber 902. Further, as a schematic representation of a reaction system, many components have been omitted for simplicity of illustration, and such components may include, for example, various valves, manifolds, purifiers, heaters, containers, vents, and/or bypasses.

The example embodiments of the disclosure described above do not limit the scope of the invention, since these embodiments are merely examples of the embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to those shown and described herein, such as alternative useful combination of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A reaction system comprising: a reaction chamber; a first precursor reactant source comprising at least one transition metal containing reactant comprising at least one of a hafnium precursor and a zirconium precursor; a second precursor reactant source comprising at least one chalcogen containing reactant; and a system operation and control mechanism, wherein the system operation and control mechanism is configured to control timing of gas pulse sequences from the first precursor reactant source and the second precursor reactant source to: contact a substrate with a vapor phase of the at least one transition metal containing reactant; and contact the substrate with a vapor phase of the at least one chalcogen containing reactant, to thereby form a transition metal chalcogenide film by a cyclical deposition process, wherein the temperature of the substrate during the steps of contact the substrate with a vapor phase of the at least one transition metal containing reactant and contact the substrate with a vapor phase of the at least one chalcogen containing vapor phase reactant is below 450° C.
 2. The reaction system of claim 1, wherein the cyclical deposition process comprises an atomic layer deposition process.
 3. The reaction system of claim 1, wherein the cyclical deposition process comprises a cyclical chemical vapor deposition process.
 4. The reaction system of claim 1, wherein the first precursor reactant source comprises at least one of a halide precursor and a metalorganic precursor.
 5. The reaction system of claim 4, wherein the first precursor reactant source comprises at least one of hafnium tetrachloride (HfCl₄) and zirconium tetrachloride (ZrCl₄).
 6. The reaction system of claim 4, wherein the metalorganic precursor comprises at least one of an alkylamide precursor and a cyclopentadienyl-ligand containing precursor.
 7. The reaction system of claim 6, wherein the alkylamide precursor comprises at least one of tetrakis(ethylmethylamido)hafnium (Hf(NEtMe)₄) and tetrakis(ethylmethylamido)zirconium (Zr(NEtMe)₄).
 8. The reaction system of claim 6, wherein the cyclopentadienyl-ligand containing precursor comprises at least one of tris(dimethylamido)cyclopentadienylhafnium (HfCp(NMe₂)₃), bis(methylcyclopentadienyl)methoxymethylhafnium ((MeCp)₂Hf(CH)₃(OCH₃)), tris(dimethylamido)cyclopentadienylzirconium (ZrCp(NMe₂)₃), and bis(methylcyclopentadienyl)methoxymethylzirconium ((MeCp)₂Zr(CH)₃(OCH₃)).
 9. The reaction system of claim 1, wherein the at least one chalcogen containing reactant comprises hydrogen sulfide (H₂S), hydrogen selenide (H₂Se), dimethyl sulfide ((CH₃)₂S), or dimethyl telluride (CH₃)₂Te.
 10. The reaction system of claim 1, further comprising a gas purifier, wherein the system operation and control mechanism is further configured to control a flow of the vapor phase of the at least one chalcogen containing reactant through the gas purifier prior to entering the reaction chamber to reduce a concentration of at least one of water and oxygen within the vapor phase of the at least one chalcogen containing reactant.
 11. The reaction system of claim 10, wherein the concentration of at least one of water and oxygen within the chalcogen containing vapor phase reactant is reduced to less than 1 part per million.
 12. The reaction system of claim 1, wherein the system operation and control mechanism is further configured to flow a carrier gas through the first precursor reactant source to transport the vapor phase of the at least one transition metal containing reactant to the reaction chamber and to flow the carrier gas through a gas purifier prior to entering the first precursor reactant source to reduce a concentration of at least one of water and oxygen within the carrier gas.
 13. The reaction system of claim 12, wherein the concentration of at least one of water and oxygen within the carrier gas is reduced to less than 1 part per million.
 14. The reaction system of claim 1, wherein the system operation and control mechanism is further configured to pre-anneal the reaction chamber, prior to film deposition, at a temperature of greater than 500° C.
 15. The reaction system of claim 1, wherein the transition metal chalcogenide film comprises a predominant (001) crystallographic orientation.
 16. The reaction system of claim 1, wherein the system operation and control mechanism is further configured to deposit a capping layer over the transition metal chalcogenide film to substantially prevent oxidation of the transition metal chalcogenide film when exposed to ambient conditions.
 17. The reaction system of claim 16, wherein the depositing the capping layer over the transition metal chalcogenide film comprises depositing the capping layer utilizing non-oxidative precursors or non-oxygen reactants.
 18. The reaction system of claim 16, wherein the capping layer comprises a metal silicate film.
 19. The reaction system of claim 16, wherein the metal silicate film comprises an aluminum silicate film.
 20. The reaction system of claim 1, wherein the operation and control mechanism is further configured to control a pressure within the reaction chamber. 